Hydratable polymers have extensive use in oilfield applications. Some common terms for these hydratable polymers may include water soluble, collodially dispersible (hydrocolloids), and water swellable. Hydratable polymers may commonly be used as thickeners or viscosifiers in well treatment fluids. Natural hydratable polymers such as guar gum, dituan gum, xanthan gum, or synthetic polymers such as hydroxy cellulose and carboxymethyl hydroxyethyl cellulose are common rheology modifiers that may be added to a variety of well treatment fluids. In fracturing fluids, the hydratable polymers may thicken and gel to hold the proppant in solution. Without the added viscosity, the proppant may settle out of solution and cause pumping problems and poor treatment results. In cementing applications, hydratable polymers may act as water-retention agents, suspending agents, lubricants, and/or friction modifiers, among others.
Despite the advantages of using hydratable polymers in well treatment fluids, such treatments may be problematic. When the hydratable polymers are added to the mixing tub in fracturing operations, they may exhibit excessive viscosity and cause the fracturing fluid to need extra hydraulic horsepower to clear the tub and be pumped down hole. The sudden increase in viscosity resulting from rapid hydration may lead to mixing and pumping problems. When these materials are added to the water at too fast of a rate, polymer clumps may be seen. These clumps may solvate to form a tough outer layer that prevents complete hydration of the interior particles. This may result in solutions with grainy texture, reduced viscosity, or the presence of insoluble particles. The high shear conditions needed to break up these agglomerations may also over shear the already hydrated particles resulting in permanent loss of viscosity.